Union chiefs have warned that the next Labour leader must reinvigorate the party's grass roots - and begin work before the devolved and local elections in May.
Billy Hayes, general secretary of the CWU, said: "I think we can use the election campaign as a way of re-engaging with our membership."
His sentiments were echoed by other union leaders, who argued at a fringe meeting at the Labour conference that the party was suffering from a malaise that could prove fatal.
"It's all very well listening to [speeches from] Tony Blair and Bill Clinton.but we are in deep trouble when our party activists aren't active," said Unison general secretary Dave Prentis.
There was also concern that the contest to find a successor to Tony Blair could drag on and damage Labour's electoral chances. Tony Woodley of the T&G said the party could not wait for nine months to resolve the issue.
He said: "It's really important that whoever we have got in place is in place before the Scottish and Welsh and English local elections next May."
Amicus leader Derek Simpson emphasised that Labour's next leader had to bring back "the four million people who voted Labour.the quarter of a million people who were members of the Labour party who have left".
There was also consensus that Labour had to rethink its attitudes to employment law and public services, in particular the NHS.
Mr Prentis said he wanted to see "clear red water" between Labour and Conservative policies on the NHS - which was "the jewel in our crown".
"We are in the absolutely ludicrous position that we have persuaded the electorate to agree to a tax increase to go into the health service but we have up to 20,000 possible redundancies," he said.
All the union leaders also agreed that a new party leader needed to listen to its members and allow more internal debate.
"We need to re-establish real democracy [in the party].I want to talk about Trident and other important issues as well," said Mr Woodley.